UICollectionView lags when scroll - swift

Question

I have a UICollectionView where i display cell that contain an png image each cell. When i display two er more cell beside each other the scroll will lag, but when i only display cells below eachother the scroll run more smotthly.
In my cellForItemAtIndexPath i got this 2 lines of coe which was recommended in another stackoverflow thread:
cell.layer.shouldRasterize = true;
cell.layer.rasterizationScale = UIScreen.mainScreen().scale
It did help a little, but not much.
The way i get the image is by making an extension to ImageView:
import Foundation
import Alamofire
let imageCache = NSCache()
extension UIImageView {
public func imageFromUrl(urlString: String) {
if let image = imageCache.objectForKey(urlString) as? UIImage {
self.image = nil
self.image = image
}
else {
self.image = nil
Alamofire.request(.GET, urlString).responseJSON{
response in
if let tilbudimage = UIImage(data: response.data!){
self.image = tilbudimage
imageCache.setObject(tilbudimage, forKey: urlString)
}
}
}
}
}
And in my cellForItemAtIndexPath i init the cell image like:
let cell = collectionView.dequeueReusableCellWithReuseIdentifier("postcol", forIndexPath: indexPath) as! PostColViewCell
cell.PostImg.imageFromUrl(firstImage["imgurl"].string!)
Display cells this way lag when scroll:
Display cells this way does not lag when scroll
Here is my whole cellForItemAtIndexPath:
func collectionView(collectionView: UICollectionView, cellForItemAtIndexPath indexPath: NSIndexPath) -> UICollectionViewCell {
let cell = collectionView.dequeueReusableCellWithReuseIdentifier("postcol", forIndexPath: indexPath) as! PostColViewCell
cell.layer.shouldRasterize = true;
cell.layer.rasterizationScale = UIScreen.mainScreen().scale
cell.layer.cornerRadius = 10
let post = self.postArray[indexPath.row]
let firstImage = post["images"].array![0]
if(post["newpost"].int! <= 1)
{
cell.NewLabel.hidden = false
}
else
{
cell.NewLabel.hidden = true
}
cell.ProfilePicture.imageFromUrl(post["user"]["photourl"].string!)
cell.ProfilePicture.contentMode = .ScaleAspectFill
cell.ProfilePicture.clipsToBounds = true
cell.NameLabel.text = post["user"]["firstname"].string! + " " + post["user"]["lastname"].string!
cell.PriceLabel.text = String(post["price"].int!) + " kr."
cell.NameLabel?.userInteractionEnabled = true
cell.NameLabel?.tag = indexPath.row
let tapped:UITapGestureRecognizer = UITapGestureRecognizer(target: self, action: "seeUser:")
tapped.numberOfTapsRequired = 1
cell.NameLabel?.addGestureRecognizer(tapped)
cell.TitleText.textColor = UIColor.blackColor()
cell.TitleText.labelSpacing = 5; // distance between start and end labels
cell.TitleText.pauseInterval = 2.0; // seconds of pause before scrolling starts again
cell.TitleText.scrollSpeed = 30; // pixels per second
cell.TitleText.textAlignment = NSTextAlignment.Left; //centers text when no auto-scrolling is applied
cell.TitleText.fadeLength = 12;// length of the left and right edge fade, 0 to disable
cell.TitleText.font = UIFont(name: (cell.TitleText?.font.fontName)!, size: 12)!
cell.TitleText.text = post["title"].string!
if(cell.PostImg.image != nil)
{
cell.PostImg.imageFromUrl(firstImage["imgurl"].string!)
}
cell.PostImg.contentMode = .ScaleAspectFill
cell.PostImg.clipsToBounds = true
//Comment label layout
cell.CommentLabel.text = String(post["comments"].array!.count)
cell.CommentLabel.textColor = UIColor.whiteColor()
// Here is the magic
cell.CommentLabel.icon = UIImage(named: "Comment")// Set icon image
cell.CommentLabel.icon = cell.CommentLabel.icon!.imageWithRenderingMode(UIImageRenderingMode.AlwaysTemplate)
cell.CommentLabel.tintColor = UIColor.whiteColor()
cell.CommentLabel.iconPadding = 5 // Set padding between icon and label
cell.CommentLabel.iconPosition = SMIconLabelPosition.Left // Icon position
cell.CommentLabel.textAlignment = .Right
//Distance label layout
if (post["distance"].double! < 1)
{
cell.DistanceLabel.text = LoginViewController.CurrentUser.CurrentLocation
}
else
{
let formatter = NSNumberFormatter()
formatter.minimumFractionDigits = 0
formatter.maximumFractionDigits = 0
cell.DistanceLabel.text = formatter.stringFromNumber(post["distance"].double!)! + " km"
}
cell.DistanceLabel.textColor = UIColor.whiteColor()
// Here is the magic
cell.DistanceLabel.icon = UIImage(named: "Location")// Set icon image
cell.DistanceLabel.icon = cell.DistanceLabel.icon!.imageWithRenderingMode(UIImageRenderingMode.AlwaysTemplate)
cell.DistanceLabel.tintColor = UIColor.whiteColor()
cell.DistanceLabel.iconPadding = 0 // Set padding between icon and label
cell.DistanceLabel.iconPosition = SMIconLabelPosition.Left // Icon position
cell.DistanceLabel.textAlignment = .Left
return cell
}